Conventional displays: Evidence for socially mediated costs of threat displays in a lizard

摘要

Threat displays are used to settle the vast majority of contests between green anoles (Anolis carolinensis). While these displays have been the subject of a number of studies, very little is understood about the information they convey. Theoretical models divide displays into several types of signals, based on the mechanism that stabilizes their use: 1) performance signals, 2) handicapping signals, or 3) conventional displays. The existence of performance displays has excellent empirical support, as do models of their use. Handicapped signalling models, especially those relating to mate-choice, have been highly influential, though little evidence suggests that threat displays are, in fact, handicapping. Most threat displays appear to be conventional, but little empirical work documents conventional signalling systems. This study investigated the use of headbob, pushup, and lateral compression displays, and concluded that headbob cadence, a discrete signal with three alternative rhythms, is a conventional display indicating impending escalation. Pushups and lateral compression displays appear not to be handicaps, since neither indicates impending escalation, and they do not correlate with fighting ability or condition.